There are 3 objectives of the proposed research: (1) to develop an isotopic marker of bowel infarction which will permit earlier diagnosis; (2) to study a variety of vasodilatators to determine which is optimal for reversing vasoconstriction of the mesenteric circulation associated with non-occlusive mesenteric ischemia of cardiac origin; and (3) to use our observations from these experiments to formulate improved diagnostic approaches and treatment plans for patients with non-occlusive mesenteric ischemia. During the first year of the project, a technic for imaging experimental canine bowel infarction with intraarterial or intravenous 99m Technetium Pyrophosphate was developed. We confirmed that the technic was not useful for the detection of ischemia but instead widespread infarction needed to be present for positive images. In addition to applying this technic in the diagnosis of patients with mesenteric infarction, we will extend our study this year to include evaluation of vasoactive substances in a canine model of nonocclusive mesenteric ischemia to determine which drug best reverses mesenteric vasoconstriction without causing deterioration in systemic hemodynamics. It is hoped that this radionuclide test and the infusion of vasodilators in patients with mesenteric ischemia will allow earlier detection of mesenteric infarction and modify the course of the disease, ultimately leading to improved survival in these patients.